Numerous medical interventions are nowadays controlled by means of intraoperatively obtained x-ray images. By way of example, x-ray images, so-called fluoroscopic images, are often recorded in real-time in order to navigate the instruments during neurosurgical or other minimally invasive interventions. The x-ray devices used for this purpose are mostly equipped with an image recording system, which allows projection images to be recorded from the most varied of projection directions so as to be able to view the examination area from the line of vision suitable in each instance. The so-called C-arm systems are popular here, such as for instance the device AXIOM Artis by Siemens AG, with which x-ray tubes and x-ray detectors are fixed to the ends of a C-arm which can be moved freely about the patient. Furthermore, the patient support can also be adjusted.
However, the two-dimensional (2D) projection images obtained in this way do not contain depth information and thus do not display any spatial details. A three-dimensional (3D) display of the changes in the image content during the entire diagnostic or surgical intervention would be ideal for the surgeon. However, with present-day imaging modalities, it is not possible to obtain 3D images in real-time.
In the prior art, the missing spatial information in the intraoperatively obtained projection images is hereby sometimes compensated for in that preoperatively recorded three-dimensional images (3D images) are view together with the two-dimensional projection images (2D images). This combination of current 2D images and spatially triggered 3D images enables the doctor to orientate him/herself in the volume during the intervention, however, no structures are visible in the preoperatively recorded 3D images. The structures are only inserted into the examination area during the intervention. Furthermore, it is difficult to spatially correspond (register) the preoperative 3D images to the intraoperative projection images.